import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.Socket;
import java.net.SocketException;

public class UdpEchoServer {
    private DatagramSocket socket=null;

    public UdpEchoServer(int port) throws SocketException {
      socket=new DatagramSocket(port);
    }
    public void strat() throws IOException {
        System.out.println("启动服务器：");
        while (true){

            DatagramPacket requestPacket=new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            String request=new String(requestPacket.getData(),0,requestPacket.getLength());
            String response=process(request);
            DatagramPacket responsePacket=new DatagramPacket(response.getBytes(),response.getBytes().length,requestPacket.getSocketAddress());
            socket.send(responsePacket);
            System.out.printf("[%s:%d] req=%s,resp=%s\n",requestPacket.getAddress().toString(),requestPacket.getPort(),request,response);

        }


    }
    public String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {


            UdpEchoServer server = new UdpEchoServer(9090);
            server.strat();


    }
}
